By Ava Politis '26
Introduction
Professional baseball's National League was the only league to exist until the American League was founded in 1901 ("American League is Founded"). While both teams were considered major leagues, the American League utilized the Designated Hitter rule introduced in 1973 ("What are the Differences Between the American and National Leagues?"). The designated hitter is a player who does not play defense and bats in place of the pitcher since pitchers are not known as the strongest hitters on the team ("Designated Hitter Rule | Glossary"). For example, from 1929-1941, pitcher Wes Ferrell only hit 38 home runs in his entire professional career, which is the most a pitcher has ever hit. On the other hand, David Ortiz hit 541 home runs as a designated hitter from 1997 to 2016 as he crushed 30-plus homers in 10 different seasons ("All time home run leaders at each position"). When interleague play occurred, and an American League team was playing at a National League stadium, the pitcher would have to hit and vice versa. In 2022, the National League officially gave in and officially adopted the Designated Hitter rule.
Although adding a designated hitter to the National League would eliminate moments like Bartolo Colon hitting his famous home run in 2016, it could allow the National League to bring up more power hitters to the plate and rest their pitchers. On the surface, having designated hitters instead of pitchers would create a more effective offense as they hit for power. They typically have more hits and home runs than an average pitcher, which would allow more runs to be produced per game. According to Braves pitcher Charlie Morton, "'I don't think anyone wants to watch me strike out on three pitches and walk back to the dugout 98 times out of a hundred'" (Kurkjian). With that being said, some pitchers were also great hitters, as Madison Bumgarner hit two grand slams in his career, which is as many as Pete Rose and Derek Jeter had in 25,248 at-bats combined (Kurkjian). This paper will investigate whether or not there is statistically significant evidence supporting the hypothesis that designated hitters' offensive production in the National League is more effective than National League pitchers.
Methods
To examine whether or not designated hitters are more effective hitters than pitchers in the National League, I will examine National League designated hitters’ production from 2022 to 2023 and compare it to the offensive production of National League pitchers from 2002 to 2021. I will exclude data from 2020 due to the Covid-19 pandemic. To further dissect these two data sets, I will conduct hypothesis tests on runs batted in (RBI) per plate appearance and strikeout rate as my two parameters. Thus, the null hypothesis is that the runs batted in (RBI) per plate appearance and strikeout rate are the same regardless of whether the batter is a pitcher or a designated hitter in the National League. The alternative hypothesis that I propose is that the strikeout rate decreases and the RBIs per plate appearance increase when the designated hitter is batting instead of a pitcher in the National League. For strikeout rate, a one-tail t-test will be conducted as strikeout rate is the proportion of a result of a strikeout per plate appearance. A one-tail t-test can also be used for RBI, as it can be viewed as the number of runs batted in per plate appearance. On-base plus slugging (OPS) would be a possible statistic to review. However, because its constituent parts, on-base percentage and slugging percentage, involve different denominators, namely plate appearances (PA) and at-bats (AB), it would be challenging to evaluate. However, if I were to compare the RBIs and strikeout rate of a National League designated hitter versus a pitcher, I would better understand how the designated hitter affects the offense. The strikeout rate will reveal which position is striking out more, leading to less productive at-bats. RBIs will reveal which position contributes more runs to a game, which is necessary for an effective offense and a win. For National League designated hitters, data from the past two MLB regular seasons will be used since that is when they were allowed to bat. For National League pitchers, data will be used from 2002 to 2021 MLB seasons, as 2002 is the farthest I can go back and when pitchers primarily batted. All data are collected from FanGraphs.
Results
Below are National League’s designated hitters’ counting statistics from the 2022 and 2023 MLB regular season.
The counting statistics were then utilized to calculate the total strikeout rate (K%) and RBIs per plate appearance.
The same process was used to calculate National League’s pitchers counting statistics and rates from the 2002 to 2021 MLB seasons (I am excluding 2020 due to the COVID-19 pandemic).
The data reveals that when a designated hitter replaces a pitcher in the line-up in the National League, the strikeout rate of the number nine spot decreases and the number of RBIs per plate appearance increases. Since the data matches my alternative hypotheses, I will conduct hypothesis tests to identify if the results are statistically significant.
To begin, I will first analyze if the change in the batter affects the strikeout rate. During that period, National League designated hitters had a total of 11799 plate appearances and struck out 2762 times (Table 1). However, National league pitchers had a total of 50753 plate appearances and struck-out 17597 times (Table 3). Due to the calculations, pitchers had an average strikeout rate of 34.67% (Table 4) while the designated hitters struckout 23.41% of the time (Table 2).
Knowing this information, I can conduct a t-test. 0.3467 is the sample mean and the hypothesized mean is 0.2341. The standard deviation of the sample is 0.15 as it was calculated in Excel with a sample size of 19 since there were 19 different seasons examined.
Since the degree of freedom is 18, I find on the t-distribution chart 3.27 falls between levels 0.005 and 0.001 to get a value of 0.003 since I am doing a one-tailed test. Since the p-value is less than 0.01, I can reject the null hypothesis and accept the alternative hypothesis that strikeout rate decreases when the designated hitter is batting instead of a pitcher in the National League.
To go deeper into my analysis, I will analyze if the change of the batter in the National League has an effect on the number of RBIs per plate appearance. National League designated hitters had a total of 11799 plate appearances with a total of 1525 RBIs (Table 1). However, National League pitchers had a total of 50753 plate appearances with 2468 RBIs (Table 3). Due to the calculations, pitchers averaged 0.05 RBIs per plate appearance (Table 4), while the designated hitters averaged 0.13 RBIs per plate appearance (Table 2).
The sample mean is 0.05 and 0.13 is the hypothesized mean. With a standard deviation of 0.10 (calculated by Excel) and a sample size of 19, I could conduct a t-test.
Discussion
The hypothesis testing implied that my results were statistically significant, meaning that replacing the designated hitter in the number nine slot in the lineup instead of the pitcher provided a more effective offense in the National League. In more depth, National League designated hitters provide a more productive at-bat since they strike out less and provide more runs for their team as they tend to hit with men on base. Even though strikeout rate and RBIs per PA provide a good representation of a good hitter, there are other ways of analyzing if a batter is effective. Analyzing statistics such as on-base percentage or slugging would have been a good way to represent if a batter can get on base and hit for power. However, I wanted to see if designated hitters provide a more productive at-bat than pitchers, so it was best, in my opinion, to analyze strikeout rate and RBIs. Throughout my research, it seems that designated hitters provide a better offense than pitchers in the National League, and there could be multiple reasons for this. Pitchers do not put a lot of focus into batting as they need to focus on pitching. Starting pitchers have pressure on them to go far into the game and give up the least amount of runs possible. Hitting a home run is most likely the last thing on their mind. Designated hitters only have to focus on hitting. They do not have to practice defensive skills and mostly have to worry about offense, giving them more time to improve their hitting abilities. Designated hitters can focus more on their opposing pitcher and pick up on their style and trends. J.D. Martinez has had an excellent career as a designated hitter thus far. He has played 776 games as a designated hitter and has 534 RBIs (FanGraphs). Martinez pulls through for his team as a designated hitter, hitting with men on base to produce an effective offense.
Even though I put hard work into this experiment, the research still has many things that could be improved. Because FanGraphs only gave me data starting in 2002, I was not able to get a holistic view of the batting of pitchers. Pitchers could have had better batting statistics in the 1900s; however, this experiment was unable to tackle that. The COVID-19 pandemic in 2020 also screwed up the data since there were designated hitters in the National League. However, it was a shorter season, and I believed the data would not have a great impact on my findings. Also, I could have used more advanced metrics like Weighted Runs Created Plus (wRC+) and Statcast data to provide more evidence. Lastly, designated hitters do not usually bat in the number nine slot since they are usually better hitters than pitchers. Therefore, they could bat in the cleanup spot where more men could be on base. Designated hitters could have more opportunities to receive an RBI, whereas pitchers who bat last would most likely bat with no one on base.
There are many more factors that I can consider in further investigation. Pinch hitters used to have a large impact in National League games as a team would strategize when it was best to input a pinch-hitter. Managers also had to research what batter would be best to put in those situations. If I had researched pinch hitters more, I would have compared them to designated hitters and see which position would provide a more effective offense. Stolen bases are another large part of the offense, and it would be amazing to see if there was a large difference in the number of bases a pitcher stole versus a designated hitter. Shohei Ohtani, a pitcher and designated hitter, is a huge outlier in my research. In the 2023 season, he had a .304 average, which was tenth in the MLB, and 44 home runs, which was 4th in the MLB. Not only is he excellent at hitting, but he is also an amazing pitcher, as he has a career ERA of 3.01. These stats led him to another MVP season (“Shohei Ohtani Career Stats - MLB”). With the success of Ohtani, there may be more pitchers that can hit and hit for power as Ohtani inspires a new generation. The designated hitter might go away once more if this does happen, and a whole new set of data might appear.
Conclusion
In conclusion, National League designated hitters produce more RBIs per game and strike out less often than National League pitchers. However, I cannot conclusively say that National League designated hitters provide a better offense than National League pitchers. Every batter needs to be productive at bat. Designated hitters seem to be doing better than pitchers as they strike out less often and hit when men are in scoring position. As mentioned previously, Ortiz has had a very successful career as a designated hitter. However, Shohei Ohtani has proven that pitching and hitting well are not incompatible. Despite Ohtani, designated hitters are outperforming pitchers in the National League in specific areas when it comes to batting. Therefore, I believe the National League made the correct decision in adopting the Designated Hitter rule, and I expect to keep seeing National League designated hitters for years to come.
References
American League is founded, 30 November 2021, https://www.history.com/this-day-in-history/american-league-founding-mlb. Accessed 22 December 2023.
Fangraphs, 24 June 2019, https://www.fangraphs.com/leaders/major-league?stats=bat&lg=nl&lg=al&qual=y&ind=0&pos=dh&type=c%2C4%2C6%2C-1%2C7%2C11%2C21&month=15&startdate=&enddate=&season1=1871&season=2023&team=0&v_cr=202301. Accessed 22 December 2023.
“All time home run leaders at each position.” MLB.com, 11 September 2022, https://www.mlb.com/news/all-time-home-run-leaders-at-each-position. Accessed 20 December 2023.
“Designated Hitter Rule | Glossary.” MLB.com, https://www.mlb.com/glossary/rules/designated-hitter-rule. Accessed 22 December 2023.
Kurkjian, Tim. “A little less 'magic': What we'll lose forever as pitchers stop hitting.” ESPN, 1 April 2022, https://www.espn.com/mlb/story/_/id/33621715/a-little-less-magic-mlb-lose-forever-pitchers-stop-hitting. Accessed 20 December 2023.
“Shohei Ohtani Career Stats - MLB.” ESPN, https://www.espn.com/mlb/player/stats/_/id/39832/category/pitching. Accessed 22 December 2023.
“What are the Differences Between the American and National Leagues?” Sports & Nobbies, 9 November 2023, https://www.sportsnhobbies.org/what-are-the-differences-between-the-american-and-national-leagues.htm. Accessed 22 December 2023.